Waiting half an hour or a full hour after eating before jumping into a pool is probably something we've all been instructed to do as kids. We never questioned it, we just believed that the effects could be less than desirable - although, given the opportunity, we'd probably still chance it anyway.
It's long been said that the practice could result in death as swimming right after eating can induce stomach cramps or simply cause you to sort of regurgitate your meal and either choke, drown, or both.
According to a piece from Lifehacker.com's Beth Skwarecki, though, swimming after eating has never actually been linked to stomach cramps, and those wouldn't kill you in any case.
Skwarecki claims to have attempted to track down the rule's origin and wasn't able to come up with anything definitive. But she did find something in a 1918 publication called How to Swim.
"A period of at least two hours should elapse between eating and entering the water, in order to give the digestive processes time to get their work well under way," Annette Kellermann wrote in there. "If the water is entered too soon after eating, especially when it is at a low temperature, the digestive process is immediately arrested, and this in itself is likely to produce a severe case of cramps, and perhaps result in acute indigestion which may prove serious."
A 1950 study debunks this, however.
"As an interesting sidelight we have made it a practice to ask at all of our classes if any student had ever had a stomach cramp while swimming," the study on cramps among swimmers claims.
"To date, after questioning over 10,000 boys, we have not encountered one person who has had one, or one person who claims to have actually seen one. ...This is amazing; to say the least, in view of the large number of drownings allegedly caused by stomach cramps. ...It appears probable that we have been perpetuating, unthinkingly, an invention of newspaper writers, which is no more than a notion, educed by untrained observers, based on the flimsiest of evidence."
If you still have doubts, consider this: competitive swimmers eat before and sometimes during long-distance swims. Of course, it might feel uncomfortable, but it's hardly fatal.
This is by no means an encouragement, if there's no real reason to go swimming right after a meal then you probably shouldn't do it. If you have to, though, you could rest assured that you'll be fine.